There is little evidence that herbicides from agronomic or industrial usage are reaching or accumulating in our water supplies in amounts to cause a pollution problem. Fish tolerance to weed killers varies with their size and species as well as with differences in the aquatic site. There may be variation to different forms of the active ingredient. Other components in a formulation may be more toxic than the herbicide itself. Therefore, the LD50of different formulations should be determined. In addition, the manner and other circumstances involving application of a herbicide may change its toxicity to water inhabitants. Our current knowledge of the effects of herbicides on fish, plankton, and other water inhabitants indicate that harmful effects with our present herbicides, when such exist, are only temporary. Available evidence suggests there is no biological magnification problem with herbicides.

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Many investigations have been made of the nutrition of plants grown in sand and water culture, and more particularly of the results of the deficiency of one or more specified ions in an otherwise complete nutrient solution. In almost every case, the deficient element was replaced in the nutrient solution by another one.Recently a method was described by HAMNER (4)1 Barley seeds selected for uniformity were planted in quartz sand in glazed 4 x 8-inch self-draining crocks. Ten seeds were planted in each crock and three crocks were used for each point of the triangle. Plants were watered with distilled water until the first leaf was about 5 cm. tall, after which they were watered on alternate days with nutrient solution and were flushed out each week with distilled water.All experiments were repeated twice later in the summer, so that a total of about four thousand plants was used. The investigations were begun in June and continued through September. Plants were grown under ordinarv greenhouse conditions of light and humidity.Two nutrient triangles were used. In the first triangle, three stock solutions, N, S, and P were prepared. Solution N consisted of 0.0045 molar KNO3, 0.0045 molar Mgo(NO3)2, and 0.006 molar Ca(NO3)2. Solu-

The herbicide 2,4-D has been in commerce and a subject for research since 1944. It is undoubtedly among the most thoroughly researched pesticides in the world. In our society, 2,4-D has played an indispensable role. It is most important in the production of our food and fiber; in the control of noxious weeds causing public health problems such as common ragweed (Ambrosia artemisiifolia L.) and poison-ivy [Toxicodendron radicans (L.) Ktze.] in the maintenance of our utility supply lines and highway and railroad systems; and as a useful tool for creating desirable wildlife habitats and beautifying our parks, golf courses, and the grounds about our homes.Recently completed toxicological studies support the conclusions of earlier studies that 2,4-D may be used without undue risk to man, wildlife, or the environment. This does not mean, of course, that we should lessen our precautions to avoid exposure to applicators, prevent spray drift from getting on bystanders, or on pets such as dogs and cats, and following general good sanitation practices in its use.There have been some reports of an association between the use of 2,4-D and NHL. However, in our opinion after considering all the toxicological and epidemiological evidence, it has not been established that the use of 2,4-D causes NHL or any other type of cancer including soft tissue sarcomas and Hodgkin's disease. As cited in this review, most scientific experts who have carefully examined all the data share this opinion.